1. Technical Field
The present invention relates to a driving force distribution system that distributes torque between right and left driven wheels in different proportions by selectively operating two electromagnetic clutches and, in particular, to the structures of the electromagnetic clutches.
2. Description of the Related Art
There is a known technique that enhances turning performance where the engine torque can be distributed between right and left driven wheels via a driving force distribution system that includes two clutches, and the torque distributed to the outer turning wheel is increased while decreasing the torque distributed to the inner turning wheel thereby generating a yaw moment in the turning direction. With regard to such a driving force distribution system, one in which the above-mentioned two clutches are formed from electromagnetic clutches has already been proposed by the present applicant (Japanese Patent Application No. 11-293467).
In the above-mentioned electromagnetic clutches, frictional engagement members are arranged in the axial direction on opposite sides of cores. The cores housing coils and armatures are arranged in the axial direction on opposite sides of the frictional engagement members, and excitation of the coils attracts the armatures toward the cores, thereby engaging the frictional engagement members. Since the cores, the frictional engagement members, and the armatures are aligned in the axial direction, there is the problem that the axial dimensions of the electromagnetic clutches increase.
The present invention has been carried out in view of the above-mentioned circumstances, and it is an object of the present invention to reduce the axial dimensions of a driving force distribution system that includes two electromagnetic clutches.
In order to achieve the above-mentioned object, there is proposed an electromagnetic clutch structure in a driving force distribution system including a first electromagnetic clutch that transmits torque from a right output shaft connected to a right driven wheel to a left output shaft connected to a left driven wheel, and a second electromagnetic clutch that transmits torque from the left output shaft connected to the left driven wheel to the right output shaft connected to the right driven wheel, selective operation of the first and second electromagnetic clutches transmitting torque between the right and left output shafts, wherein each of the first and second electromagnetic clutches includes a coil, a core housing the coil, an armature arranged so as to adjoin the core in the lateral direction, and frictional engagement members arranged on the inside, in the radial direction, of the core, and wherein the frictional engagement members are engaged by pressure of a pressure part of the armature, the pressure part extending further inward in the radial direction than the core.
In accordance with the above-mentioned arrangement, the first and second electromagnetic clutches of the driving force distribution system have the armature arranged so as to laterally adjoin the core housing the coil, and have the frictional engagement members arranged on the inside, in the radial direction, of the core, and the frictional engagement members are engaged by pressure of the pressure part of the armature, the pressure part extending further inward in the radial direction than the core. It is therefore possible for the axial dimensions of the driving force distribution system to be reduced compared with an electromagnetic clutch where a core, frictional engagement members, and an armature are arranged in the axial direction.
The first electromagnetic clutch and the second electromagnetic clutch of the present invention correspond to a right electromagnetic clutch CR and a left electromagnetic clutch CL respectively of the embodiments below. The frictional engagement members of the present invention correspond to clutch discs 26R and 26L and clutch plates 27R and 27L of the embodiments below.
Modes for carrying out the present invention are described below by reference to embodiments of the present invention shown in the appended drawings.